1. Technical Field
This invention relates to the field of very high and ultra high vacuum systems, for example, vacuum systems used in semiconductor manufacturing. More specifically, the invention pertains to the field of vacuum seals and methods to detect seal damage.
2. Description of the Prior Art
A number of processes are used for depositing or removing thin film material from a semiconductor substrate. Typically, these processes occur in an etching or deposition chamber under a state of very high or ultra high vacuum. The chamber contains a highly reactive environment such as produced in a chemical deposition reaction between a carrier gas and a precursor, producing a solid reaction product.
In spite of rather large differences among various vacuum systems, all of them possess some elements in common. FIG. 1 shows a very high vacuum system device intended for operation in the 10−6 to 10−9 Torr pressure range. The actual lower limit of pressure which will be reached will depend on the choice and design of components as well as on the care taken in fabrication and cleaning. The major components involved in this system are; a process chamber 21, mechanical and diffusion pumps (not shown), piping 24, and seals 26. Other components not shown include vacuum gauges for assessing vacuum conditions, valves, baffle, cold trap and miscellaneous hardware including a getter ion pump, and protective devices, etc.
Ultra-high vacuum systems are used in many different applications involving semiconductor manufacturing, nuclear particle accelerators, and research apparatus. The manufacturing of VLSI (Very Large-Scale Integration) products, specifically sub-micron devices formed on 300 mm substrates, are extremely dependant on every process step, in particular, on the numerous processes using high and ultra-high vacuum chambers to fabricate sub-micron circuit lines. That is to say, seal reliability is of major concern since undetected seal damage may cause a high number of defective substrates before the processing problem is recognized.